The present invention relates to a carrier tube for package dyeing of textile products such as yarn and the like and, more particularly, to a collapsible carrier tube.
In the textile industry, carrier tubes are utilized to support yarn during a dyeing process. The yarn is wound onto a carrier tube at high speeds to form a substantially cylindrical package of yarn on the tube. The yarn-supporting tubes are then supported on the spindle of a dye kettle for application of a dye medium. The tubes are commonly formed with mating ends to facilitate nested stacking of multiple yarn packages on one spindle. A dye medium is introduced into the dye kettle via the spindle for radial passage of the dye through the carrier tube and the supported yarn package. The carrier tubes are perforated to provide the necessary passageway for the dye from the spindle to the yarn. Known carrier tubes include tubes having intersecting elements which form a lattice type structure to provide the necessary perforations.
The prior art includes tubes made from metals such as stainless steel. However, metal tubes require thorough cleaning before reuse to prevent a previously applied dye medium from contaminating a dye medium subsequently applied. Known carrier tubes also include tubes made from plastic. Material and manufacturing cost efficiencies relating to molding of plastics facilitate the mass production of tubes for generally disposable use thereby eliminating the need to clean the tubes for re-use.
The perforations in the tube providing for passage of the dye medium should not excessively reduce the structural integrity of the tube. The perforated carrier tube must possess sufficient strength to carry loading applied to the tube. For example, the tubes typically incur an axial load after mounting on a spindle to seal the ends of the tube and to ensure that the dye medium will pass radially through the yarn rather than out of the ends of the tube.
Another factor to be considered is the thermal expansion of the tube and spindle. The dye medium used in the dyeing process is typically heated to a temperature that is slightly lower than the melting temperature of the plastic. This temperature results in a substantial softening of the plastic, making deformation under load relatively easy. Also, since the plastic material of the tube expands at a greater rate than the metal of the spindle, an additional axial load is created on the tube during the dyeing process. Considering this load and the relative softness of the plastic at the elevated temperatures, structural integrity of the tube may become compromised (at least to the extent of creating problems during unwinding of the dyed yarn).
Prior art tubes have incorporated flexible, or collapsible, structures to provide for axial compression in response to compressive loading such as that induced by restrained thermal expansion. Examples of axially compressible carrier tubes are shown in U.S. Pat. Nos. 4,986,488 to Windhosel et al. and 4,946,114 to Becker et al. In Windhosel, ring sections of a central portion of the tube are interconnected by webs. Each of the interconnecting webs is twice bent at right angles to provide flexibility in the axial direction. The webs function in the nature of springs rather than load bearing ribs of a lattice structure. In a similar fashion, Becker discloses ring sections interconnected by spacing members. Each of the spacing members throughout the tube is bowed to provide for compression of the spacing members in response to compressive axial load.
The heat of the dye medium tends to shrink the yarn within the yarn package. The winding of the yarn on the tube creates a radially inward load around the circumference of the tube. To prevent damage to the yarn in response to compressive loads induced by the shrinkage of the yarn against the tube, on which the yarn is wound, prior art tubes have incorporated flexible, or collapsible, structures providing for radial collapse.
Examples of radially compressible tubes are shown in U.S. Pat. No. 5,632,451 to Pasini and European Publication 0471353A of Zimmermann. Pasini discloses alternating transversely deformable longitudinal members and rigid longitudinal members. Stiffening tacks connect the alternating longitudinal members. Application of compressive hoop load to the tube, from shrinking yarn for example, causes deformation of the transversely deformable members and radial collapse of the tube as the rigid members adjacent the deformable members are directed towards one another. In Zimmermann, a lattice structure includes ring sections that do not intersect with each of the longitudinal members and are instead secured to some of the members by bowed elements. The bowed elements permit flexibility and radial compression of the carrier tube under compressive hoop loading.
A potential problem associated with known carrier tubes that provide for collapse of the tube, especially in the axial direction, is pinching of the yarn between collapsing portions of the carrier tube. The potential for pinching is greater where the collapsibility of the tube is concentrated such that a large percentage of the overall collapse of the tube occurs at each location of collapsible structure.
It is an object of the present invention to provide a collapsible carrier tube for supporting a wound package of yarn in a dyeing process in which predefined collapsible portions are interspersed within the structure to permit the tube to maintain its structural integrity in response to yarn reactions to the dyeing process.
According to one embodiment of the present invention, there is provided a carrier tube for dyeing yarn packages. The carrier tube comprises a series of axially spaced rings and a series of columns or ribs extending longitudinally along the tube. The ribs and rings define the wall of the tube and form a lattice structure to support yarn wound thereon and having openings therein to permit the dye to be introduced from inside the tube to the yarn wound on the exterior of the tube. Each of the ribs includes at least one reduced load carrying section, which is capable of compressing in response to an axial loading of the tube during the yarn dying process. In a preferred structure, multiple reduced load carrying sections may be interspersed on each of the ribs within the lattice structure.
According to another embodiment of the present invention, the lattice structure of the tube includes at least one reduced load carrying members within each of the rings such that application of a hoop load results in compressive deflection of the reduced load carrying members. In a preferred structure, multiple reduced load carrying members may be interspersed along the length of each of the ribs within the lattice structure.
It should be understood that the reduced load carrying sections on the rings and the reduced load carrying members on the ribs may be combined within the overall lattice structure. The number and form of the reduced load carrying sections and members may be varied as desired, depending on the operating conditions, materials, yarn, temperatures and other factors involved.